1.mysql 某一列中所有值的出现次数

SELECT VPDM,count(vpdm) FROM ipos_qtlsd GROUP BY VPDM ；

2.将时间类型转成int类型

SELECT UNIX_TIMESTAMP('2012-2-1') from DUAL

3.将int类型转换成时间类型

SELECT  FROM_UNIXTIME('1332950400') FROM DUAL